Lathe chuck



L. E. WHITON LATHE CHUCK March 21, 1939.

Filed July 20, 1956 I A TTORNEY Patented Mar. 21, 1939 UNITED STATES PATENT OFFICE Application July 20,

2 Claims.

My invention relates to adjustable chucks and has for its main object to provide means for indicating the amount of adjustment.

One object is to provide an exceedingly simple and inexpensive device for aiding in the ac curate adjustment of the jaws. It is especially directed to chucks having jaws which are independently adjustable although it is also adapted to combination scroll and independent jawed chucks.

It is common practice to apply concentrically marked circles on the face of the chuck for indieating to some extent the radial adjustment, but it is not practical to place the jaws in precise concentric accuracy by this method. Therefore, I further employ a, special socket in the adjusting screw and a corresponding wrench which is made suiiiciently strong for the work and yet is so shaped that it can be inserted in only one position in the socket. By properly designing the socket and wrench I am able to very accurately estimate or measure and indicate the adjustment of the jaws without requiring any additional mechanism or expense.

' Essentially, the improvement contemplates the employment of a special shaped socket in the end of the screw, and with a corresponding wrench which consequently can be inserted only in one position. The wrench handle is preferably provided with an enlargement at one end, so that when the wrench is applied, the ball will be in a plane through the prolonged screw axis, at right angles to the parallel faces of the keystone socket. The angular position of this ballend will then give a very close approximation to thousandths readings on the adjustment of the sliding jaws which are moved by the screw.

Fig. 1 is a face view of a three jaw chuck with my invention applied to it.

Fig. 2 is an edge view and partial section. Fig. 3 is a perspective view of the special wrench.

Fig. 4 is a detail view showing various angular adjustments of the wrench.

Fig. 5 is a face view of a four jaw chuck. Fig. 6 shows the end of an adjusting screw with another form of special socket.

The form shown in Figs. 1 and 2 is a geared 50 scroll combination chuck with a body 1, a scroll plate 8 (rotated in any suitable manner), a number of toothed slides or carriers 9 actuated by the scroll plate, jaws Ill slidable in grooves in the body and screws II rotatably supported by 55 the slides 9 and meshing with teeth in the backs 1936, Serial No. 91,448

of the jaws in the usual manner in chucks of this t e.

ach screw is provided with a socket I2 for the wrench I3 which fits it. The socket, in cross section, is in the shape of a key-stone or trapezoid with two parallel sides and two inclined sides and the handle [4 is preferably at right angles to the planes of the parallel sides.

As a matter of convenience in designing the key-stone socket, the diagonal lines through a square socket were opened at the top 7 7 each way from the-center line, and correspondingly closed at the bottom. A circle is then drawn corresponding to the required design from the corner of the socket to the bottom diameter of the screw thread, which will leave the same strength of material at all four corners of the key-stone socket, as in the case of the square socket. If the intersections of the radial lines and the circle so drawn are then connected, the resulting outline is the key-stone socket, which results in only one possible position for inserting the coacting wrench.

When, by the universal geared scroll movement of the jaws, they are closed into approximately close relation with some one of the concentric circles on the face of the chuck, a slight adjustment of one or more of the screws will bring the jaws into true relation with the concentric circle, it being noted that when the chuck is true, the wrench handle and ball-end will project at right angles to the face of the chuck, the axis of the wrench handle being then parallel to the axis of the lathe spindle.

The screw l l in the form shown has a pitch of ten threads per inch. A rotation of the wrench handle of 90 will accordingly move the jaw I0 through A, of or .025 inch.

The following table shows just what turn of the wrench is required to produce certain adjustments, i. e.

There is a wide application of this form of screw socket and wrench, in the ordinary four jaw independent chuck, whereby, by means of this indicating adjustment, the radial movement of the jaws can be very closely estimated by the operator in thousandths of an inch.

In other Words, if a piece of work is being trued up in an independent chuck by means of an indicator and the indicator shows an eccentricity, say of .010", an adjustment of the chuck jaw of .005" will be the correct adjustment to true the piece, or vice versa, the jaws may thus be placed for some required eccentricity.

This convenient means of visually estimating the adjustment will be a desirable feature in all regular independent jaw chucks without the added cost of supplying graduated or fprotractor dials or indicators, although, if the operator desires to apply them, the chuck body or the jaws may be marked with lines radial to the socket to indicate the angular positionscorresponding to the radial adjustment of the jaws to beproduced by corresponding turns of the wrench.

In Fig. 6 I have shown a modified form of socket to receive a corresponding wrench. In this case the cross sectional shape of the socket is hexagonal but with an additional corner or recess to receive a corresponding projection on a hexagonal wrench. It is thus possible to insert the special wrench in only one position. This form of socket, however, also permits the use of an ordinary hexagonal wrench which could be applied in any one of several positions which may better'suit the operator's convenience.

The absolute shape of the section of the socket recess is not essential but it is of the greatest importance to so designthe parts'as to permit of the application of relatively powerful pressure and at the same time ensure suflicient strength for the area of the engaging parts.

The concentric circles on the face of the chuck for convenience are generally so laid out as to differ by convenient fractions such as inch or inch-variations in radius. These circles may also be stamped toindicate the diameter or radius.

Itwill be understood from the foregoing that all of the screw threads will be 'cutso that the positions of the sockets in all of the screws will be exactly alike when the screws are in corresponding positions, i. e. at zero or any other radial advancement or retraction and that the faces of all of the jaws will be ground alike so that when a truly cylindrical piece is held by the jaws all of the sockets will'be in the same rotative positions. The jaws of the chuck may therefore be set precisely true at any time without requiring any other mechanical'devices;

-I claim:

l. Achuck having jaws for holding the work,

on the jaws and on the face of the chuck for indicating the approximate position of each jaw, a wrench adapted for engagement with each screw by a projection and socket type connection of generally polygonal cross section, an extension on said wrench for applying force at a distance from the screw axis to rotate said wrench and screw, the improvement for quickly and visually obtaining a more accurate setting of a jaw than is obtainable with said reference means but without the previously necessary cost of applying a graduated dial, protractor or the like to the end of a screw or to the edge of the chuck, which comprises said projection and socket-connection between the wrench and screw being so shaped that the wrench can be engaged with a screw in only one angular position and that being such that the wrench extension is visually oriented with respect to some prominent feature of the chuck such as the jaw axis or chuck face when the said reference means align, whereby the angular displacement between said wrench extension and prominent feature may readily .indicate the position of a jaw relative to said reference means with substantial accuracy.

2...A chuck having jaws for holding the work, an actuating screw for each jaw, a wrench adapted for engagement with each screw by a projection and socket type connection, an extension on said wrench .for applying force at a-distance from the screw axis to rotate said wrench and screw, the improvement which includes said connection being so shaped that the wrench can be engaged with the screw in only one position and all of the jaw actuating screws having threads in precisely the same relation to said connection whereby when the wrench extension is similarly oriented and angularly positioned with respect to some prominent feature of the chuck such as the jaw axis or chuck face, the same prominent feature being used for each screw, then the jaws will be similarly and accurately positioned or else radially displaced from one another by an amount equal to-or a multiple of the thread pitch, whereby the jaws may-be'accurately positioned without the necessary expense of a protractor or the like on the ends of the screws or the edge of the chuck and whereby the ready visual determination of the angular position of the wrench extension indicates the relative position of a jaw.

LUCIUS E. WHITON. 

